Air Motors

AutomationScrewdriving technology Air motors Air tools

D 6000 E 5.2007

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Experience since 1918

Right from the start, we chose compressed air as the drive medium for thousands of motors in the most varying application areas.

This extensive experience resulted into today’s drives and fulfills the highest quality demands. These drives are manufactured according to the strictest quality-standards and of course they are certified in accor-dance with the international norms of the DIN EN ISO 9001. High-quality materials, our own heat-treatment of all-important motor-parts and the profound production-precision of our modern CNC-machines, assure the highest possible life span of all motor-variations.

The use of a modern building-block con-struction in connection with modular, com-puter-aided construction-programs, gua-rantees a high flexibility, shortest reaction times and an especially attractive price- to performance-ratio.

Motor-Constructions

Numerous basic principles have develo-ped in the course of the evolution of the air-motor. However, only few variations have continuance. Today, the vane-motor is the most enduring variation. Beside that, there is the gear-motor for highest speeds, without vanes as wear-parts, or turbines.

Air-Piston Motor of 1926 Air-Vane Motor of 1997

QS-Certificate

Basic principles of air-motors

Vane-Motor Gear-Motor Turbine Piston-Motor

Variation: – Vane Amount – Straight Toothing – Radial – Radial – Vane Array – Beveled Toothing – Axial – Axial – Disk Armature – Herringbone Gear – Tangential

Sketch:

approx. max. Speed 60 000 rpm 140 000 rpm 120 000 rpm 10 000 rpm

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Bearing Cover Vane Rotor Cylinder Bearing Cover

Rotor

Air-Vane-Motor

Function of the Vane-Motor

All vane-motors essentially consist of the rotor, which circulates in an eccentrical-ly offset perforation of the rotor-cylinder. Because of this eccentrically offset perfo-ration, the vanes form working-chambers, the volume of which increases in the turn-direction. Because of the expansion of the condensed supply air, the pressure energy is converted into kinetic energy, and there-fore, results into the rotation of the rotor.

For motors with one turn-direction, an increased turnangle for the expansion of the air is available. Therefore, these motors reach a somewhat higher efficiency.

The total efficiency-grade is essentially defined by the leak-loss on the front-end of the motor. Highest production-tolerances (≤ 0.01 mm) are essential for the unique performance-density of the DEPRAG vane-motor.

In accordance to application requirement, the rotor contains 3 to 6 vanes. A higher vane quantity results into a greater start-safety at high friction-loss. The tangential array of the vanes, provide a larger vane-height and with it, a higher motor endurance.Virtually all DEPRAG motors include a specialized surface-treatment of the rotor-cylinder, which increases the vane life span.

In the practice, the vane motors has shown to keep a relative constant orbital-speed, which is according to motor design between 25 and 30 m/sec. The unloaded speed of a motor essentially depends on the motor-diameter.

Right Rotation Reversible

R L R

Sectional Sketch of Vane-Motor

Radial Tangential

Vane Array

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Vane Spring

Vane motor with automatic start

Engraved code for use in potentially explosive areas

Starting ConditionsDuring the operation of an air-motor, the vanes are pressed against the wall of the rotor cylinder by the centrifugal force, which seals the working-chambers against each other. If there are special requests in regard to the start-torque, suitable measures must be met to guarantee an automatic start.For example: – spring-loaded vanes – pin-guided vanes – thrust-rings – vacuum induction, etc.With the above options, it is possible to achieve a start-torque, which is approxima-tely 1.5fold of the nominal torque.

Quality of the Compressed AirOilfree operation is possible on special request, especially for use of air motors in the food-industry or chemical industry. Non-lubricated use will result into a 10-15% per-formance-decrease. For a continued, oilfree operation we offer special vanes, which are made of custom-material.

Ex CertificationUp to now, the use of air motors in explosi-on endangered environments was possible without limitations.A related certification was therefore not necessary.With the guideline 94/EG, better known as ATEX 100, the qualification of air motors for the use in EX-environments must now be proven.

A Type Certification of an independent check ing institution will ensure the approveduse of the motors of the series 67- for the field ”Not Mining” in zone 1 (gas or dust contaminated environment), for mediumswithin the explosion group IIC, with an approved surface temperature of 80 - 95°C.

The motors are now marked with: • II2GD c IIC T6 (80°C) for a power of 90 to 600 Wand • II2GD c IIC (95°C) for a power of 1200 W

Lubricated operation always improves a motors life span and operational behavior. For a correct air-preparation, dryers and maintenance-units, existing of filter and oiler, are necessary.

In regard to air-quality according to ISO8573-1, we recommend: Class Residue of Oil Content Residue of Dust Residue of Water particle pressure mg/m3 oz./cu.ft. size mm mg/m3 oz./cu.ft. dew-point 0C g/m3 oz./cu.ft.

Dry Air 3 1 1.03 · 10-6 0.005 5 5.14 · 10-6 -20 0,88 0.90 · 10-3

Lubricated Air 4 5 5.14 · 10-6 0.015 8 8.22 · 10-6 +3 6 6.17 · 10-3

Gear MotorsBecause of the necessary high speeds, gears are often required for a maximum torque to speed adaption. Precision planetary-gears are best suited to achieve high torques with smallest design-sizes. The necessary reduc-tion ratio will be achieved by consecutively staged gear-steps (maximum 1:10 per step).

Additionally, if the installation condition requi -res it, there is the possibility to reach very high torques at low speeds by implement-ing spur-gears or worm-gear drives.

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ComparisonAir-Motor / Electric-Motor

Frequently, the unfavorable total-energy use is often seen as a disadvantage of the air-motor. Indeed, if one looks at the total-efficiency including the energy-output, the air-motor does not look favorable with an approximately 30 % efficiency. That the air-motor has nevertheless asserted itself, in the entire drive-technology, as an essentialalternative, emphasizes its numerous advantages. When compared with the total cost-estimate of the machine, the energy consumption plays no crucial role, especially when small drives with low duty-cycles are used.

Design Size

The main-advantage of the air-motor is its high performance-density, which is only about 1/5th of the mass or 1/3rd of the size of an electric motor with a comparable performance. This is particularly important with all hand-held machines, but also with robotic-systems or CNC-machines, where the drive has to be indexed.

Size-Comparison of Air-Motor / Electric-Motor

Power Characteristics

The power output performance of the air-motor is virtually constant over extensive speed-margins. It can also be operated in a wide field of alternating loads. The power output can be easily adjusted, by changing the operating-pressure, and the speed is perpetually variable, by the reduction of air-volume.

Load Capacity

The air-motor can easily be stressed to a full standstill; it even tolerates a negative turn-direction if the load is increased. The motor always reaches its full power-output and there will be no damage to the motor! The air-motor starts again immediately, once the load is removed and this conse-cutively, even when motor operates with-out a pause.

Temperature-Behavior

Through the expansion of the compressed air, the motor cools the generated frictio-nal heat. Under load, the motor gets cooler than the environmental temperature; only when idling, a rise in temperature may occur. The motor is therefore temperature-insen-sitive, and an overheating through over load is practically impossible.

Safety

In principle, compressed air is an unpro-blematic energy-bearer. Contrary to elec-tric motors, air motors have no electrical connections, which could cause harm to the operator or equipment.

Maintenance

Air operated drives are extremely robust. The internal overpressure prevents the penetration of dust or dirt. Only the very affordable vanes are to be exchanged as wear-parts. Necessary repairs are simpleand can be done easily and safely by a trained maintenance person. No electricity specialist is necessary.

Further details and valuable hints can be taken from our leaflet D 0090 E ”Preventivemaintenance and repair of air-operated tools”.

Air-Motor

Electric-Motor

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Characteristicsof the air-vane motor

Torque

The torque of unadjusted vane-motors increases, at constant operating-pressure, almost linearly with decreasing speed. The air-motor can easily be stressed to a full standstill, where it reaches the so-called stationary- or stall-torque. The theoretical stall-torque corresponds approximately to double the nominal-torque, reduced by the standstill-loss, in the practice to about 1.9fold of the nominal-torque.

The so-called startup- or starting torque against the load, is lower than the stall tor-que. It depends on the vane array at the start-up time. The fluctuation amounts to approximately 100 to 150 % of the nomi-nal-torque.

Speed

With vane-motors, speeds can be reached up to 80 000 rpm. In the speed-area of ≤ 15 % of the maximum-speed, the motor runs in an unstable area with strong torque- and speed-fluctuations. This unstable con-dition is caused by insufficient insula tion of the vanes at slow rotor-speed. Significant is the maximum- or speed idling and the so-called nominal-speed, amounting to approximately 50 % of the speed idling.

Performance

A parabolic performance-curve results from the linear torque-process, with the maximum output at nominal-speed. This output-maximum is identified, according to the nominal-speed, as the nominal power-output. Each operating-point below the nominal power-output is reached with 2 speeds, which lie symmetrically to the output-maximum. Therefore, the air-motor cannot be selected for performance alone, but in the first place for the necessary tor-que, as well as the corresponding speed.

Air-Consumption

The air- and with it the energy-consump-tion, is determined by the leak-loss and the output from chamber-volume, chamber-number and speed. The air-consumption increases linearly with the speed and rea-ches its maximum with the unloaded-speed. Vane-motors usually cite a specific air-con-sumption per kilowatt of 1.4 m3/min at smaller motors, up to 1 m3/min at bigger motors.

Torque (M) %Power (P) %Air-Consumption (Q) %

200

180

160

140

120

100

80

60

40

20

Stall-Torque

Starting-Torque

Nominal-Torque

10 20 30 40 50 60 70 80 90 100

Nom

inal

-S

peed

Spe

edid

ling

Speed (n) %

100

90

80

70

60

50

40

30

20

10

Nominal-Power

P

M

Q

Characteristics of the air-vane motor

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Operating-Pressure

All references in regard to performance, speed, torque and air-consumption are normally based on the nominal operating-pressure of 6 bar (85 PSI).Fluctuating operating-pressures influence this data. In a theoretically sealed motor, all values change with the square of the abso-lute pressure. In the practice, the flow- and leak-loss is therefore influenced by the pressure-change, so that performance and torque, change only linearly with pressure-alterations.

Pressure-Loss

The total-efficiency of the air-drive is essen-tially defined by 3 sorts of losses. Friction-loss derives from vane- and gear-friction. The loss-element is essentially decided by the material-combination of Rotor/Vane and Vane/Rotor/Cylinder, as well as the corresponding surface roughness and lubrication. Here, production-tolerances and surface-treatment-procedures play an impor-tant role.

Selection and Designof Vane-Motors

Design of air-operated vane-motor & Dimensioning

In accordance with the known output requirement, load-torque or necessary performance, the formulas allow the calcu-lation of the needed motor-size in connec-tion with the required speed.

The operation of air-drives with non-lubri-cated air, generally deteriorates the friction-ratio in the motor and results into a speed loss, down to approximately 90 % of the nominal speed.Further losses are caused by cross-section reductions, deflections and inconstant con-nections, which can lead to a considerab-le flow-resistance. These flow-losses also reduce the total-efficiency of the motor.

In addition, leak-loss arises because of operating- and production conditional - requirements. Particularly, these losses origi nate between rotor and rotor-cylinder in the upper dead center, as well as axially between rotor and vane and the double-ended bearing covers. These leak-losses can be reduced to a minimum, by applying tightest production-tolerances.

Q

Power (P) %Speed (n) %Torque (M) %Air-Consumption (Q) %

130

120

110

100

90

80

70

60

50

40

30

20

10

3 4 5 6 7

Pressure (p) bar

Nominal-PowerNominal-SpeedNominal-TorqueAir-Consumption

P

M

n

Nom

inal

-Pre

ssur

e 6

bar

Pressure (p) Power (P) Speed (n) Torque (M) Air-Consumpt. (Q)bar / PSI % % % %

7 / 99 121 103 117 1176 / 85 100 100 100 1005 / 71 77 95 83 834 / 57 55 87 67 673 / 42 37 74 50 50

Influences of the Operating-Pressure

M [Nm] · n [rpm]9550

P [kW] =

P [kW] · 9550n [rpm]

M [Nm] =

Power [HP] = P [kW] · 1.34Torque [in.lbs] = M [Nm] · 8.85

With the values for torque and speed, the most suitable motor, normally the next-biggerone, can be selected from the shown tables. The necessary flow pressure for the most suitable operating-point, can be determined from the known nominal-sizes, by linear interpolation.

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Connection-Lines:

Control

For the control of air-motors with one turn-direction, a simple 2/2-way-valve is used. A simple two-way-valve can also control motors with two turn-directions, provided the motor has an integrated hand-reverse-lever. Otherwise a 5/3-way valve is necessary,

so that the respectively unused rotor-side can be exhausted. As an alternative, two 3/2-way-valves are also possible. In every case, it is important that the selected valve has a sufficiently large airflow capacity.

Diagram for connection of compressed air-motors

2 2

4

3

12

13 2

1

1) Maintenance Unit(filter with water separator, pressure regulating valve and oiler)

2) Silencer3) 2/2-way valve4) Motor

2

4

3

2

2

13

5

24

1

Air MotorReversible

2

4

2

2

1

13

212

1

2

3

Air MotorReversible

Air MotorRight-/Left-Rotation

1) Maintenance Unit(filter with water separator, pressure regulating valve and oiler)

2) Silencer3) 5/3-way valve4) Motor

1) Maintenance Unit(filter with water separator, pressure regulating valve and oiler)

2) Silencer3) 2 x 3/2-way valves4) Motor

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Torque-/Speed-Reaction with air-regulation

Regulation

The required torque- and speed-values of the operating-point can be adjusted by a simple pressure-regulation. The flow-pres-sure of a perfectly selected motor, should lie between 4 and maximum 6.3 bar.

In the practice, the optimal operating-point is reached by an overlaid regulation of pressure and air-volume. Either an exhaust- or supply air throttling can be used for air-

regulation. Supply air-throttling leads to a concave-, and exhaust air-throttling to a convex torque / speed. Reversible motors have to be used with throttle-valves instead of throttles.

The speed of the motor changes not only with the pressure-regulation but also when the load changes. With complete load removal, the speed increases up to the speed idling. This high speed is not allow-able for all drive-requirements. For those

Torque (M) %

Exhaust Throttle

Supply Air Throttle

Speed (n) %

100

80

60

40

20

20 40 60 80 100

200

180

160

140

120

100

80

60

40

20

100

90

80

70

60

50

40

30

20

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Nominal-Torque

Nominal-Power

Speed (n) %

10 1009080706050403020

Nom

inal

-S

peed

Spe

edid

ling

Torque (M) %Power (P) %Air Consumption (Q) %

M

Q

P (regulated)

P (unregulated)

cases, regulators are integrated for speed-limitation. Motors with a speed-regulator decrease the speed from speed idling to nominal-power output by 10-30 %.

Characteristics-Comparison of the unregulated and the regulated air-motor

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Picture 1:Lifting device on the sheet-cutter of a paper machine.

Picture 1

Application-Examples

The diverse design-variations, the simple construction, the low performance-weight, the large speed-range and the motors explosion-proof abilities, enable the air-motor to participate in a wide application-spectrum:

– General Mechanical Engineering: Production machines, injection machi-

nes, paper machines, textile machines, calendering machines, conveyor-controls, pumps, turn- and rotary-tables, dividing-apparatus, strapping equipment.

– Mining- and Conveying Technology: Propulsion for extraction- and loader-

machines, hydraulic pumps for mines, ventilator, blow + seal equipment, con-veyer belts, shaker conveyor, winches, hoists.

– Smelters and Power Plants: Tipping device, oven-doors, drive of

impeller-pans, locking gates in glass-, steam- and water pipes, sluice gates.

– Nuclear-Technology: Manipulator, assembly- and coating-pro-

cessors.

– Ship-Construction: Boat-davits, derricks, ladder winches,

cargo-hatch-drives, anchors winches

– Chemical Industry: Agitators, pumps and blowers, air-drives

for gates and valves, actuator units.

– Foods Industry: Pumps, handling equipment + drives,

mixing machines.

– Medical Industry: Drills, surgical tools, dentist-tools.

Besides the numerous motors of our stan-dard motor line, we specifically manufacture the most different and specialized motors for your application. Our engineers would like to assist you with the design and imple-mentation. Following are some examples:

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Picture 2:Air drive on a chain-welding machine.

Picture 3:Strapping device for packaging with steel bands. The compact and powerful air-drive enables the ergonomic design of hand-held machines.

Picture 2

Picture 3

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Picture 5:Horizontally auger with an air-drive of approx. 5 kW.

Picture 4:Conveyer belts for extreme operating-environ ments, i.e. mines or foundries with DEPRAG air-drives.

Picture 5

Picture 4

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Picture 6:Powerful and explosion-proof air-motors, used as drill-carriage-drives on mobile drills during underground mining.

Picture 7:Air drive on a blind-gate in pure-glass-pipe-lines of a blast furnace.

Picture 6

Picture 7

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Picture 8:On ships, particularly tankers, explosion-proof DEPRAG air-motors are used for the heaving of lifeboats.

Picture 8

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Picture 9:Air-motors used for different surgery-devices; optimal performance-density enables their use in impeded application-conditions, i.e. steam-sterilization.

Picture 9

Accessories:

We recommend for the optimal operationof air-motors, our accessories, such as maintenance units with filter and oiler, pressure-regulators, specialized lubrication oil, oil-resistant pressure-hoses, and all applicable couplers and plugs. For more details, please refer to our catalog D 3340 E.

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DEPRAG SCHULZ GMBH u. CO.P.O. Box 1352, D-92203 Amberg, GermanyKurfürstenring 12–18, D-92224 AmbergPhone (0 96 21) 371-0, Fax (0 96 21) 371-120www.deprag.cominfo@deprag.de